Shawn Bixby borrowed $39,000 on a 150-day, 9% note. After 80 days, Shawn paid $4,200 on the note. On day 113. Shawn paid an additional $6,200. Use ordinary interest. a. Determine the total interest use the U.S. Rule. (Do not round intermediate calculations. Round your answer to the nearest cent.) Total interest b. Determine the nding balance due use the U.S. Rule. (Do not round intermediate calculations. Round your answer to the nearest cent.) Ending balance due